Staff balloting include those working on the Croydon, Epsom, Kingston, Richmond, Sutton, Wandsworth and Wimbledon Guardians, the Richmond & Twickenham Times, the Surrey Comet and the News Shopper (Bexley, Bromley, Dartford, Gravesend, Greenwich and Lewisham editions) as well as their associated websites.

Laura Davison, NUJ national organiser, said: “The situation on these titles has become critical in terms of the strain put on the staff.

“What is so upsetting is that we have a group of professional journalists who are thwarted from being able to produce work to a high standard, but it seems the management doesn’t care.

“Young trainees who start off thinking they are beginning their dream career are dejected and burnt out by the workloads and lack of support.

“More experienced staff are leaving because of the way they are being treated and there is nowhere else for them to go – in vast swaths of the south east, Newsquest is the only newspaper employer in town. They don’t want to go on strike.

“They are loyal to their readers and care passionately about the titles but their management refuses to listen.

Last summer, members in south London went on a 10-day strike over redundancies, understaffing and to persuade the management to pay trainees a living wage.

They won support from the London Assembly and the council leaders of Merton, Kingston, Sutton, Richmond and Croydon councils who complained to the then Newsquest managing director.

The NUJ said more than 300 years’ worth of experience had been lost from Newsquest’s south London titles in the past two years because of redundancy or reporters leaving because of “savage cuts” to newsrooms.

The ballot will conclude at noon on Friday 9 September.

Newsquest has been contacted for a comment.

The NUJ’s stress survey found 88 per cent often or always worked intensively, 36 per cent said they had unachievable deadlines, more than half (52 per cent) did not have supportive feedback on their work, 56 per cent did not have sufficient breaks and 88 per cent said they were not consulted about changes at work.

Comments from staff completing the survey included:

“I have had no support from my editor or those above throughout my time at Newsquest, despite being given an unrealistically large and high-pressure workload in my first job as a trainee, and being the sole trainee expected to complete a large paper alone. Changes are agreed behind closed doors with no consultation with reporters and apparent total disregard of how it will affect them.”

“There is plenty of support and encouragement in the office from colleagues, but not enough from the company. Each desk is working with the bare minimum of reporters and every reporter is stretched to their limits to cover everything going on in their patch. Stress levels are exceptionally high at times because of this.”

“The company’s strategy of managed decline has created a pervasive negativity in the office. Staff are expected to produce a lot of work in little time. The opportunity to produce quality, in-depth journalism is lacking for that reason, which gnaws at reporters who know they are capable of better journalism than they currently produce. That said, their attitude in the face of all this is generally good and good work is still done here. Newsquest’s approach has soured the collective attitude to the point that even trainee reporters are leaving the company in disgust.”